Imposing yourself on a game is linked to having confidence in your own abilities. Lucas' confidence is being undermined, partially at least, by a section of the support that seem to want him to fail.
People were saying Torres wasn't a 20 goals per season striker before he signed. Aquilani will play a good bit higher up the pitch than Alonso did, I reckon he'll be getting into shooting positions a fair bit more as well.
I don't we over-achieved, the team played at a level they knew they were capable of far more consistently last season than any other season under Rafa.